Circuit breaker control



Sept. 23, 1952 Filed July 15, 1951 A. coNANGLA 2,611,796

CIRCUIT BREAKER CONTROL 2 SHEETS-SHEET 1 .BY MTM Sept. 23, 1952 A, :QlxflANGLAv 2,611,796

CIRCUIT BREAKER CONTROL Filed July 15 1951 l 2 SHEETS- SHEET 2 ff fz! ///2 111 4 v// A.: c: zzz

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(awe/v Jaume IN VEN TOR.

Patented Sept. 23, 1952 :il y,

s the conductors 36 and 31 for the operating mechanisms of the circuit breakers, as will now be described.

The circuit breaker I, in addition to the auxiliary contacts 23, is provided with auxiliary contacts 4|, which are normally closed when the circuit breaker-is closed and open when the circuit breaker is open. Thecircuitbreaker is also provided with a second set of auxiliary contacts 42 which are open when the circuit breakerpis;

closed and closed when the circuit breaker is open. The auxiliary contactsl 4| 'are'connected' to the winding of a trip device4 43 which is pro-V vided with a plunger engaging a latch 44 on theV circuit breaker I I. Auxiliary contacts4| Aare also connected to the contacts .450i an undervoltage inthesystem will of course remain unaffected.

In theabove system Ythe operator has no con- "troi to determine which of the loads shan receive power from the emergency source. In some instances it is desirable that he have such a control so that he may selectively control any load he may-desire to the emergency source. Such f an arrangement is disclosed in Figure 2.

relay 46 connected across the normal-supply" source at buses I2. The undervoltagerelay 46 is also supplied with contacts 41 which are connected at one-terminal to the control 4power source 35 and at the opposite terminal to the auxiliary contacts 42 of circuit breakerI I. Manual'tripping of circuit breaker 22 is eiected by energization, ofv relay 29. The-auxiliary contacts 42 are connected over a conductor 28 toa closing magnet coil of the circuit -breaker 22. The

opposite terminal of the .windingof closing mag-frv Y net .5| yis connectedv over auxiliary contacts 29 (closed when thek circuit breaker22isopen and open when the 'circuit breaker.` is fully closed) and yIn FigureL 2f I have shown a circuit breaker III which connects a main source of power (not `shown)` feeding over the lines I|2 to the bus II4. -Connected to the bus 4 are a series of loads ||5 and IIS: protected by individual circuit breakersl `I1 and ||8 respectively. Although only two loads are here illustrated. itwill be understood, of cours'eg'th'at there may be many other loads. In the illustration here `provided theloads y VI I5 and IIS arej designatedV as the non-essential over conductor 52 to the-control power source.

` Y Theoperations of this system areas follows:

Normally the circuit breaker II is closed and Y "feeds energy' frornthe normal source at line I2 to 'the individual feeder circuits land loads such ln the event of-a failure atthe normal source flot' supply, the voltage Yacross the buses I2 will drop below a predetermined value and the undervoltage relay 46 will be de-energized and its solenoid will thereuponoperate .to effect closing- .'of 'the contacts 45 and 41. Y Asaresult of the closingof contacts 45V an obvious energizing circuit will be completed over the contacts45 and the auxiliary contact 4| of` circuit Ybreaker II will 'operate to open the circuit de-energize the trip .winding .43 by thecpening of contacts 4| and will complete an venergizing circuit for the .closing magnet-.5I of circuit breaker 22 over an obvious energizingv circuit from the control power source over contacts 41 of undervoltage relay 45 and auxiliary contact 42 of the circuit breaker-| Into the closing magnetS'I and line 52. Energizing ofthe closing magnet 5| will operate the circuit breaker V22 toclose its contacts connecting the emer-` gencysource2| to the loads.

A i A further result of the `opening 'of Ycircuit" "breaker II is to complete an energizinggcircuit for the trip coils 3| and 32 ofv circuit breakers A:lj-Hand I8, respectively, over obvious energizing circuits from the control power source '35 over conductor vr36 through winding 3| and 32xin parallel over closed auxiliary contacts25 and 26 through the closed-auxiliary contacts 2310i cir- Y cuitbreaker I| and the closedv auxiliary con- .Ltacts 24 ofcircuitbreaker22..(the latter auxiliaryv loads and Votherloads, which vare essential, it will be understood,l connectedto busA I I4 'ori asimilar feeder, will'V remainunaffected bythe operations tobe described.

An emergency source of powei-^-feedingover -the line I 2 IA isprovided with anemergency power supply circuit breaker `|22 1 which;` when closed,

will feed power tothe bus I I4. Y

The circuit breaker-I I I is iprovided witha pair of auxilary contacts |23 vwhich'areclosed-when as.' I5 and I6. At this tmecircuit breaker 22 vis open, thus' disconnecting the kemergency source firomthe-feeder andload-circuits.

the circuitr breaker I I |-`jis` open and are open when the circuit breaker IIIl'is 'closedi-l Circuit breaker |22 is also provided with al pairY of auxiliary contacts |24 and .|82 whichare closed 'when the circuit breaker I 22 .L is closed andv open .when Athe circuit '.breakerI22 is open; .Circuit breakers I|1 and `I;|8 are' each :providedwithzauxiliary contacts |25, I26;;respectively, .,Whichare closed when their respective circuit breakers are, closed and open when their.respective circuit breakers are open.

Circuitbreakers' |.|1, and-I I 8 are also provided Y with latching'mechanisms -for holding the respective circuit breakers in. contactengagement position against individual-biasingspringsy in a manner well known rin` the. art,y until the latches arev released by the energizationfof .their individual trip magnets I3I and |32., .Igt will be understood that all the circuitbreakers here shown are. schematically illustrated and ,are `provided with the usual closingand tripping. mechanism, as for example, illustratediin Patent No..2,348,228. A control Vsource of Apower^|35 feeds lenergy over the conductors -|36 and |31 for Vthe operating mechanisms of the circuit' breakers.

`The circuit breaker III ,1 in 'addition to the auxiliary contacts |23, fis"provided1 with auxiliary contacts I4I, which are inormally i closed' 'when the circuit breaker is'closed and openywhen the circuit breakeri'is open. c The circuit `breaker is also provided with-'a set-cfV auxiliary-pairs of contacts V|8| and I 42- whichfare'v open when the circuit breaker is-"closed andploscdwhen the circuit breaker-is open. The-auxiliary contacts 4| are connected to the winding of atripmagnet |43 which .visfpro'vided with `aplunger engaging a latch |44 on -thecircuit breaker II I. Auxiliary contacts |4| arealso connected to the con-.-

tacts |45 of an undervoltage relay |46l connected across thenormal supply source-at Vbuses II2. The undervoltagerelayL I 46 l is also supplied* with circuit breaker |22.

contacts |41 which are connectedy at one terminal to the control lpower source |35 and at the opposite terminal to the auxiliary contacts |42 of circuit breakerill. The auxiliarycontacts '|42 are connected over a conductor |28 to a closing magnet |5I of the circuit breaker |22. The opposite terminal of the winding of closing magnet I5I is connected over conductor |52 to the control power source. The operations of this system are as follows: A

Normally the circuit breaker III yis closed and feeds energy from the normal source at buses vII2 to the individual feeder circuits and loads such as I|5 and |I6. At this time circuit breaker |22 is open, thus disconnecting the emergency source from the feeder and load circuits.

In the event of a failure at the normal source of supply, the voltage across the buses II'2 will drop below a predetermined value and the undervoltage relay` |46 will be `de-energized-y and its solenoid will thereupon operate to effectgclosing of the contacts |45 and |41. As a result of the closing of contacts |45 an obvious energizing circuit will be completed over thecontacts |45 and the auxiliary contact |4I of circuit breaker III for energizing the trip coil |43. Trip coil |43 will thereupon operate its solenoid, withdraw it from the latch |44 and the spring on the circuit breaker ||I will operate to open the circuit breaker. This will disconnect the normal supply source from the load circuits. At the same time it will de-energize the trip winding |43 by the opening lof contacts AI4I and will complete an energizing circuit for the closing magnet |5| of circuit breaker |22 over an obvious energizing circuit from the control power source '|35 over contacts |41 of undervoltage relay |46 and auxiliary contact |42 of the circuit breaker III: to the closing magnet I5I and line |52. Energizing of the closing magnet |51 willoperate the circuit breaker |22 to close its contacts connecting the emergency source |2| `to the loads.

Other loads in the system will of course remain unaffected. 1 v

It will be noted that up toA this'point the circuit breaker and its operation are' identical with that described in connection with Figure l. However. in the present application applicant has provided an additional pair of relays I6| and |62, each provided with its individualsolenoid and contacting members |63 and |64 for the relay IBI and |65 for the relay |62. In addition,fthe feeder circuit breakersl|1 and II8 have been provided'with auxiliary contacts I1 I 'and |12 for circuitbreaker II1 and auxiliary contacts |13 and |14 for circuitbreaker II8. When now, in the manner described above, the circuit breaker III is opened and circuit breaker II2- is closed, an energizing circuit is completed` for the relay winding |62 over the contacts |63 of -relay I6| and over the auxiliary contacts IBI of circuit breaker III and auxiliary contacts |82 of Energization ofy the relay |62 will result in the closing of the contacts |65 which completes energizing circuits for the trip coils vof thetwo'feeder circuit breakers |I1 and IIB and these two circuit breakerscontrolling energy fed to the non-essential loadsare opened.

The opening of the" circuit lbreakers I I-'I' and IIB will vnow-complete an energizing circuit for the relay IIIr over kthe contacts |14 and- I1-2`A of circuit breakers |`I8 and I I1, respectively, which are now in open position andover the contacts I8I of circuit breakerfl I I fnow'openl" and contact |32 of circuit breaker `I22-'(now closed).

Energization of the relay ISI will result in the closing contacts |64 which completes a self-locking circuit for the relay I6 I. It rwill also, however, open the contacts |63. v

The closing of the self-locking contacts |64 provides an energizing circuit for the relay |6| which is now independent of the condition ofthe load circuit breakers II1 andv IIB so that irrespective of whether these circuit breakers are open or closed, relay I6I will remain energized so long as circuit breaker III is open and circuit breaker |I2 remains closed.

This, it will be noted at the outset, is a distinction over the circuit arrangement shown in Figure l. In Figure l, the energizing circuits for the respective trip coils of circuit breakers I1 and I8 are c-ompleted over their own auxiliary contacts. Thus it is impossible for an operator to close either circuit breaker I1 or I8 so long as circuit breakerV II is open and circuit breaker '22 closed. Each time the opera"- tor attempts to close thecircuit for eithervv circuit breaker I1 or I8, their individual trip coils are immediately energized to trip the circuit breaker. l In the modification shown in Figure 2 upo the opening of contacts |63, the relay |62 is deenergized and there is no longera prepared energizing circuit for the trip coils of circuit breakers I I1 and II8 over contacts |65. The operator may now manually `reclose these circuit breakers by completing the energizing circuit for their respective closing magnets or by manual operation (not shown) in the manner well known in the art. Closing either one or both of these can be achieved without completing the circuits for the trip coils, although their trip coils were in the first instantenergized when switching from the main or normal power supply to the auxiliary power supplyoccurred.

This, as will now be clear, is achieved bythe provision of the relays I6I and |62.' Normally the trip coils of the circuit breakers I I1 and I|8 were prepared for energization over circuits controlled by the relay |62 which relay was energized when the transfer occurred. However, upon completion of the transfer and the opening of the two non-essential circuit breakers, relay IBI is locked energized and in turn opens the circuit for the relay |62.

. Although I have shown several illustrations Y of circuit diagrams for carrying out my invention, I wish to be limited only by the appended claims.

I claim: f v 1. In an electrical system having a first and a second source of power for feeding electrical en-r ergy to loads, including loads designated nonessential; a first circuit breaker having an open and a closed position for controlling energy supply from said first source of power; a second circuit breaker having an open and a closed position for controlling energy supply from said second source of power; a trip magnet operable when energized to trip said first circuit breaker; a closing magnet operable when energized for operating said second circuit breaker to its closed position; an undervoltage relay operable respon# sive to a Voltage failure of said first source'f'or completing an energizing circuit for said trip magnet, an energizing circuit for said closing magnet controlled by the operation of saidffirst circuit breaker to its open position and the opera-A tion of said'under'voltage relay forl operating said second circuit f-vfbreake'rto its" closed position; 'Va

. 5. \In an electrical system; having a;first and a second source of power for feeding Lelectrical .energy to loads including loads designated .non-

essential; a'nrst circuit breaker having an open `and a closed position for controlling energy supply from saidiirst source-of powerasecondcircuit breakerhaving an open and a closed position for controlling energy supply from said second source of power; a trip magnet operable when energized to trip said first circuit breaker; a closing vmagnet operable whenenergized for operating said second circuit breaker to its lclosed position; means including an undervoltage relay operable responsive. to a voltage failure of-said yfirst source for. completing an energizingcircuit for said trip magnetand the energizing circuit forsaid closing magnet' for operating said second circuit breaker to its closed position; acircuit breaker foreach of said: designated non-essential loads, each circuit breaker having van open and a closed position; a trip magnetfor each of said last mentioned circuitk breakers; -a rst relay; a second relay; means controlled by saidfirst circuit breaker for energizing said first relay; energizingvcircuits for said trip magnets of said circuit breakers of saidnon-essentialloads controlled by the energization of said. rst relay; means responsive tothe operation of said circuit breaker'for said non-essential loadsfor energizing said second relay; said second relay when energized de-energizing said vfirst relay to permitvreclosing of said circuit breakers for said non-essential loads and a self-locking circuit for said iirst relay.

6. In an electrical system having aiirst and a second source of power for feeding electrical energy to loads including loads designated nonessential; a first circuit breaker having an open and a closed position for controlling energy supply from said first source of power; a second circuit breaker having an open anda closed position for controlling energy supply from said second source of power; a trip magnet operable when energized to trip said first circuit breaker; a. closing magnet operable when energized for operating said second circuit breaker to its closed position; means including an undervoltage relay operable responsive to a voltage failure of said first source for completing an energizing circuit for. said trip magnet and the energizing circuit for said closing magnet for operating saidsecond circuitrbreaker to its closed position; a circuit breaker for each of said designated. non-essential loads, each circuit breaker having an open and a closed position; a trip magnet foreach of said last mentioned circuit breakers; means.- controlled by the opening of said first circuit breaker for operating said last mentioned trip magnets; means operable following the opening of said circuit breakers for said `non-essential loadsl for locking open said energizing circuitsv for said trip magnets; yand closing mechanism for reclosing said lastmentioned circuit breakers.

'7. In an electrical system havingy a first and a second source vof power for feeding electrical energy toloads including loads designated nonessential; a first circuit breaker having an open and a closed position for controlling energy supply from said first source of power; a second circuit breaker having an open and a closed position for controlling energy supply from said second-source of power;` a trip magnet operable when energized to trip said first circuit breaker; a closing *magnet operable when energized for operating said second circuit breaker to its closed position; means includingkan undervoltage relay ,operable responsive to a voltage failureof said rst source for completingian energizing circuit for said trip magnet and Athe energizing circuit -for said closing magnet for operating said second circuit breaker to its closed position; a circuit breaker for each of .said vdesignatednonressential loads, each circuit breaker having an open1 and a closed position; a trip magnet for each of said last mentioned circuit breakers; means wcon, trolled by the opening of said first circuitbreaker for operating said last mentioned trip magnets; and means operable following the opening of said circuit breakers for said .non-essential loadsfor locking open said energizing circuits for said trip magnets; y c n i 8. In an electrical system having a first andA a second source of power for feeding velectrical energy to loads including loads designated vnonessential; a first circuit breaker having anopen anda closed position for controllingenergysupply from said first source of power; a second cir.- cuit breaker havingan open and a closed position for controlling energy supply from said second source of power; a trip magnet operable when energized to trip said iirstcircuit breaker to its open position; a closing -magnetfoper'able when energ-ized for operating said .second circuit breaker to its closed position; van rundervoltage relay operable responsive toa voltage failure of said first source for completing an energizing circuit for said trip magnetto operatesaid first circuit breaker to its open position; an energizing circuit for said closing magnet controlled by the operation of said rst circuit breaker-toits open position and the operation ofV said underf voltage relay, said closing magnet when-encre gized operating said second circuit breaker to its closed position; a circuit breakerfor each of said designated non-essential loads, `each ycircuit breaker having an open and a closed position; a. trip magnet for each of said last mentioned circuit` breakers; means controlled by the opening of said rst circuit breaker for operating. said last mentioned tripmagnets; means operable following the opening of said circuit breakers for said non-essential loads yfor locking open vsaid energizing circuits for said trip magnets;A and closing mechanism for reclosing said last mentioned circuit breakers. y

9. In anelectricalwsystem having a first and a second source. of power for feeding electrical energy to loads including loadsk designated nonessential; a first circuitfbreaker having an open and a closed position for controlling energy supply from said first source ofpower; a second circuit breaker'having an openand a closed position for controlling energy supply vfromsaid second` source of power; atrip magnet ,operable when energized to trip said flrst circuitvbreaker to itsopen position; a closing magnet operable when energized for operating said second circuit breaker to its .closed position; an undervoltage relayfoperable responsive to a voltagefailure of said first source for completing an energizing 4circuit for said trip magnet to operate said first Acirfcuit breaker toits open position; an energizing circuit for said closing magnet controlled by the operation of said rst circuit breaker to itsopen position and the operation of saidundervoltage relay, said closing magnet when energized oper ating said secondcircuit breaker to its closed position; avcircuit breaker for eachof said designated non-essentialloads, eachcircuit breaker havingy an ropen and a closed lliQSition; rali-,rip

Asaid--non-essential loads `for locking` openi said energizing circuits for said trip magnets.

I '510: In` an electrical system yhaving a liirst and a second? sourceof power for feeding electrical energy; toy loads includingloads designated nonessential; a first-circuit breaker having an open and a closed position for controlling energy supplyvl from'said' rst source of power; a second circuit breaker having'an open and a closed position for'controllingl` energy supply from saidsec'- ond source of power; an electric trip device operable when energized to trip saidiirst-circuit vbreaker toits open-position; V a closing magnet `operable whenenergized for operating said sec- 'ondL circuit breaker toits closed position;` an undervoltagerelayoperable responsive to a voltage failure ofl said'v first source for completing an en 'e'rgizingjV circuit for said` electricy trip device to operate said-nrst circuit breakerV toits open position; anenergizing circuit for said closing magnet controlled by theroperatio'n ofV said rst circuitbreakerjto its'openposition andthe operationofsaid 'undervoltage relay,r said -closing magnet 'when' energized operating' said second circuitgbreaker tov its closed position; a circuit breaker for each of zsaid designated non-essential loads; veach circuit'rbreaker having an open and aycl'osed position; an-e1ectrictrip device for each of saidr last mentioned circuitbreakers; a rst relay; -a'second` relay; said rstrelay having' an energizing` circuit therefor effected byV said second`-re1ayde-energized; said first circuit breaker in; itsA open` position 'and said second circuit hreaker'inV its closed position;` energizing` circuits for'- said` electric--trip Vdevices of saidY circuit breakersiof said non-essential loads controlled by; the energization of Vsaid first relay and' said iirst circuit'breaker'in its open position and sec'- ond circuit-breaker in' its closed position; an energizing' circuit for' said second relayA eiected by said circuitv breakers for said non-essential loads in their open'position', and said first circuit breakerinopen position and said second circuit breaker in closed position, said second relay'when energized opening the energizing' circuit of' said rst 'relay to` permit reclosing of" said circuit breakers forsaid non-essential loads and a self'- lockin'g' circuitrforv said first relay controlled by said' first circuit breaker in open position and saidssecond circuit breaker in closed position.

A 11. In an electrical system having a iirst and a second source. of power for feeding electrical energy tolca'ds including' loads designated nonessential; a first circuit breaker having' an open andaclosedposition for controlling'energy supply. `from said iirst source of power; a second cir- Cuitbreaker, having an open and aclosed position. for. controlling energy supply from4 saidmsecond source of power; a trip magnet operable when energized to trip said iirstcircuitV breaker .to its. open` position;, a closingimagnet operable when-energized for operating said second circuit breaker toits closed position'an' underyoltage relay operableresponsive to a voltage failure of said, firstL source ,for completing an energizing circuit for said trip magnet toA operate said first circuitbreaker to itstopen, position; an energizing circnit'for said closing magnet controlled bythe operationtofLsaid rstcircuit'breaker to its-open position and the operation of said undervoltage 132 reiay; saidv closing; magnet when'zenel'afizfid'fn operating said second circuity breaker Lto' its'closed kposi'tiona circuit'breaker for each of' saiddesig'- nated non-essential loads each circuit 'breaker 'having 'anI open" andV af closed position;` a `trip magnet-'foreach of `saidy last mentioned1circuit breakers; a first-relay; a second relay; said rst relay having an energizing' circuit therefor effected by said second relay' cie-energized, said rst' circuit' breaker inl its open position and said second circuit breaker-in its closed position; en'- ergizng' circuits for said" trip magnets of said circuit breakersof' said' non-essential loads controlled bythe energization offsai'd4 rst' relay and said first' circuit 'breakerv` in' its open'L position'and second circuit breakerin its' closedA position; `an energizing' circuitfor' said second relay -eiected bysaid circuit breakers for said non-essential loads in 'their'open position, and saidrstcircuit breaker in open position and said secondv circuit breaker in closed position, said second-relay when energized 'opening theY energizing' circuit of said first` relay'V to permit' reclosin'g' or said circuit breakers for said non-essential loads and-a selfilocking circuit' for" said firstl relaycontrolledby said iirst circuitbreakerin open position andi said second circuitbreaker inA closed position; f

12. In an electrical systemA havingv a rst' and a second source of: power` for feeding' electrical energy'to loads including loads designated nonessential; a rst circuit breaker having an open anda closed position for controlling'energy' supply fromsaid first source'of power; al second circuit breaker having an open-and: a closed position for controllng'energysupply from said secondl source 'ofi power; a trip magnetA operable whenY energized' to trip' said firstv circuit' breaker to its 'open-position; aJ closing magnet operable when energized 'for' operatingsaid1 second"v circuit breaker4 to its closed` position; an undervoltage relayoperable responsive to a voltage failure of said rst' source for'completing-'an' energizing cir'- cuit 'for said `trip magnet t`ooperate said first circuit' breaker to4 'its-open position; an energizing circuit' for said closing magnet controlled' by the' operationjof' saidrst circuit` breaker to' its open. position, said closing` magnet' when energized' operating said secondi circuit'breaker to its closed'A position'a circuit breaker for each'of said designatedV non-essential loads, each circuit breaker having' an open and a closed' position-j' a trip magnet foreachv of "said last mentioned circuit4 breakers; a iirstV relay; av second relay; said rst relay"having an energizing' circuit therefor affected by said firsty circuit breaker' in its open positionand, said second circuit breaker in its closed position; energizing circuits for said trip magnets ofv saidV circuit breakers of said nonessential loads controlled by the energization of saidv iirst relay and said rst circuit breaker in its open position and second circuit breaker in its closed position; anenergizing'circuit for said second relay eifected by said circuit' breakers for said non-essential loads` in their open position, and said'rst circuit'breaker inopen position and saidV second circuitA breaker inl closed position, said' second relay when energized opening the energizing circuit ofi said rst relayvto permit reclosing of said circuit breakers for' said` nonessential loads-and a self-locking circuit for'said iii-st relay controlled byI said" first-circuit breaker in open position" and said second circuit-'breaker in closed position;

13; In an' electrical-system; having a'iirst' and a second source of' power for feeding electrical 13 energy to loads including loads designated nonessential; a irst circuit breaker having an open and a closed position for controlling energy supply from said rst source of power; a second circuit breaker having an open and a closed position for controllng energy supply from said second source of power; a trip magnet operable when energized to trip said first circuit breaker;

a closing magnet operable when energized for l operating said second circuit breaker to its closed position; means including an undervoltage relay operable responsive to a voltage failure of said rst source for completing an energizing circuit for said trip magnet; and the energizing circuit for said closing magnet for operating said second circuit breaker to its closed position; a circuit l. breaker for each of said designated non-esseni.

tial loads, each circuit breaker having an open and a closed position; a trip magnet for each of said last mentioned circuit breakers; a iirst relay; a second relay; said rst relay having anv energizing circuit therefor effected by said first y circuit breaker in its open position and said second circuit breaker in its closed position; energizing circuits for said trip magnets of said circuit breakers of said non-essential loads controlled by the energization of said iirst relay and said rst circuit breaker in its open position and 'second circuit breaker in its closed position; an energizing circuit for said second relay effected b yfsaid Ycircuit breakers for said non-essential loads in their open position, and said iirst circuit breaker in open position and said second circuit breaker in closed position. said second relay when energized de-energizing said iirst relay to permit reclosing of said circuit breakers for said non-essential loads and a self-locking circuit for said iirst relay controlled by said 'first circuit breaker in open position and said lsecond circuit breaker in closed position.

AMADO CONANGLA.

No references cited. 

